Lifting devices for raising automobiles and other objects having an irregular distribution of weight are well known. They have a base, a frame on which the object is placed, and a lifting mechanism for raising the frame and object.
The lifting mechanism usually consists of a pair of interconnected hydraulic lifters with the hydraulic lines and equalizing cables on the floor. A protective floor cover is provided to protect the lines from damage by dollies, carts or lifts that are used to install or remove auto parts, such as a transmission for example. However, this cover provides a bump which is an obstacle in the movement of these auxilliary devices.
In another version a cross-bar at the top connects with the vertical base beams. The hydraulic lines and equalizing cables are placed on the cross-bar to eliminate the need for the protective floor cover that was a hinderance in the first version. However, having the cross-bar at a fixed height posed the problem of damaging the lifted object if it was lifted too high. A sensing device was needed to halt the vertical rise when the object got too close to the cross-bar. This type was unsuitable when used with limited ceiling space.